That is correct. Like Objective-C the compiler statically removes ARC when it can prove it doesn’t need it (or when you annotate it because where you’re getting it from is manually managing and giving you ownership of the reference). So within a function or cross function with LTO (although it looks like swift doesn’t yet have LTO [1] so I’m not sure about cross-module optimizations).
> When receiving a return result from such a function or method, ARC releases the value at the end of the full-expression it is contained within, subject to the usual optimizations for local values.
Quote from [2] (section 6 has the full details about optimizations). I believe [3] might be the compiler pass.
There actually is some elision that happens at runtime if you install an autoreleasepool if I recall correctly.
I did actually work at Apple so that’s where my recollection comes from although it’s been 8 years since then and I didn’t work on the compiler side of things so my memory could be faulty.
[1] https://github.com/apple/swift/pull/32233
[2] https://opensource.apple.com/source/lldb/lldb-112/llvm/tools...